I'll echo what Rob is saying, you can also walk-in to any AiS store and get the same deal, you can even just grab a SIM and set it up yourself on the MyAiS app.
You aren't going to get a non-B without already having the business established, and you definitely aren't going to get a work permit without having 2m in capital for the business and 4 Thais working for you too.
unlikely, all the rules and requirements will probably be announced on the 1st of June but I don't see it being fully implemented and made law before September
Yes, you can convert a tourist visa to an ED visa. However most schools will require a minimum of 45 days left on the visa in order to start the process for the ED conversion.
I could be wrong and if I am, I am sure someone will correct me, but similar to the Non-O, with the Non-OA you can apply for a 1 year extension. However this will require either 800k in a Thai bank account 2 months prior to applying or 65k+ in monthly transfers for 1 year.